Thermal-State Analysis On Key Parts Of Numerical Control Form Grinder

With the quick development of machine tools in high speed, high feed speed and high precision, higher demand of machining accuracy and thermal stability are requested. Among all the errors, errors caused by thermal deformation account for forty to seventy percent, therefore, it is of great significance to study the thermal characteristics of machine tools. In this paper, thermal characteristics of key parts including the spindle system and the column of a numerical control form grinder are analyzed by thermal networks method. The content of this paper is part of study on key technologies of a seven -five axis numerical control form grinder, supported by a grand science and technology special project of Zhejiang province.The main content of this paper includes:In chapter 1, the present study,development of thermal characteristics and thermal network have been summarized, the background of the project is introduced; this paper studies the key parts of the machine tool including the spindle system and the column of a numerical control form grinder.In chapter 2, three basic heat transfer styles and the elements of temperature field are elaborated; the heat transfer style of a numerical control form grinder is analyzed in accordance with three basic heat transfer styles.In chapter 3, the fundamental principles and steps of thermal network have been elaborated; the thermal structure and heat sources of the numerical control form grinder are analyzed, thermal mechanism is considered, this chapter paves the way for building the thermal network model of the key parts of a numerical control form grinder.In chapter 4, according to the structural components of the spindle system, heat sources are found out; calculation formulas of the heat capacity are deduced. Under certain working condition, partition power network of the spindle system is carried out in accordance with the heat transfer line, heat transfer coefficients of heat sources and all structural components are calculated. Thermal resistances are conducted according to the classification of different heat transfer styles, and formulas for calculating various kinds of heat resistances, heat balance equations are established, temperatures of the notes are obtained by solving the equations through MATLAB, influences to temperature distribution are also considered.In chapter 5, heat sources are found out on the basis of structure of the column—key part of the numerical control form grinder, the unite division of the physical model is engaged using thermal network method, the temperature variation curves of important temperature notes are obtained under certain working conditions. The analysis result is compared with the measured data detected from the column, and is also proved to be accurate and reliable, the source of the errors between the two is analyzed, and the influence rule of the parameters to the key temperature notes is obtained by simulation analysis. A thermal excitation device is invented and is used to compensate the temperature difference under certain model setting conditions, the feasibility of this device is proved by the temperature detection results, which provides theoretical basis for the following thermal error compensation and the method is of important practical value to improve the machining accuracy.In chapter 6, the paper is wholly generalized, some assumptions have been put forward, and the following research work is prospected.